I have a client that is the court appointed fiduciary of his Aunts estate.  His Aunt passed away in 1984 and she had a house that was not sold until 2022 and for whatever reason, an estate return was never filed.  I am trying to establish the basis of the property as a step up is not valid and the closest I can come up with is the assessment of 18K from the 1999 timeframe (property sold for 207K).  My clients lawyer has contacted a real estate agent that is going through some old MLS listings on similar homes sold in that area in that timeframe to help with the basis.  The issue is that I am running out of time as my extension expires on 9/15/23.  I have been trying to get an answer on the availability to extend a second time until the basis information is received but I have not been able to come up with the correct method to do this. 

Is it possible to get a second extension and what is the proper method to process it